perl的Getopt::Long和pod::usage ？

来源：

http://www.cnblogs.com/itech/archive/2012/08/07/2627267.html

代码：

需要显式地定义变量且初始化。例如optionX。

如果没有定义变量且显式初始化，且没有在命令行指定选项，则选项对应的变量将为未定义。

 #!/bin/perl-5.8.3/bin/perl$
 use warnings;
 use strict;

 use Data::Dumper;
 use Getopt::Long;
 use Pod::Usage;

 our $g_opts;
 our $optionX=''; #if not defined in command line, it will be empty string
 sub parse_opts{
     my $result = GetOptions(
                     "optionA=s" => \$g_opts->{'optionA'},#string
                     "optionB=s" => \$g_opts->{'optionB'},#string
                     "optionC=i" => \$g_opts->{'optionC'},#integer
                     "optionD=f" => \$g_opts->{'optionD'},#float
                     "optionX=f" => \$optionX,
                     "optionY=f" => \$optionY,
                     "verbose"   => \$g_opts->{'verbose'},#flag
                     "quiet"     => sub { $g_opts->{'verbose'} =  },
                     "help|?"    => \$g_opts->{'help'}
                   );
     if(!($g_opts->{'optionA'})){
         &pod2usage( -verbose => );#exit status will be 1
     }
     if($g_opts->{'help'}){
         &pod2usage( -verbose => );#exit status will be 1
     }
 }

 &parse_opts();
 print("\n$optionX\n");
 print($optionY); #if not defined in command line, it will be undefined
 print($g_opts->{"optionB"});

 foreach my $key (keys %{$g_opts}){
   if(!$g_opts->{$key}) {next;}
   print($key . "=" . $g_opts->{$key} . "\n");
   }
  exit();

  __END__  =head1 NAME
  sample - Using Getopt::Long and Pod::Usage
  =head1 SYNOPSIS
  sample [options] [args ...]
  Options:     -optionA         optionA
    -optionB         optionB
    -optionC         optionC
    -optionD         optionD
    -verbose         verbose
    -quiet           noverbose
    -help            brief help message
  =head1 OPTIONS
  =over   =item B<-help>  Print a brief help message and exits.  =back
  =head1 DESCRIPTION
  B<This program> will read the given input file(s) and do something
 useful with the contents thereof.  =cut